Note 2 - Revenue and Product Costs - Contract Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Balance at January 1, 2022	$ 265
Balance at June 30, 2022	344
Current portion	178	$ 155
Long-term portion	166	$ 110
Customer Deposits [Member]
Balance at January 1, 2022	43
Additions, net	4
Transfer to revenue	(43)
Balance at June 30, 2022	4
Current portion	4
Long-term portion	0
Deferred Revenue [Member]
Balance at January 1, 2022	265
Additions, net	148
Transfer to revenue	(69)
Balance at June 30, 2022	344
Current portion	178
Long-term portion	$ 166